Eurasian blue tit

Cyanistes caeruleus

The Eurasian blue tit is a small passerine bird in the tit family Paridae. The bird is easily recognisable by its blue and yellow plumage, but various authorities dispute their scientific classification.

Eurasian blue tits, usually resident and non-migratory birds, are widespread and a common resident breeder throughout temperate and subarctic Europe and western Asia in deciduous or mixed woodlands with a high proportion of oak. They usually nest in tree holes, although they easily adapt to nest boxes where necessary. Their main rival for nests and in the search for food is the larger great tit.

The Eurasian blue tit prefers insects and spiders for its diet. Outside the breeding season, they also eat seeds and other vegetable-based foods. The birds are famed for their skill, as they can cling to the outermost branches and hang upside down when looking for food.

Appearance

The Eurasian blue tit is usually 12 centimetres long with a wingspan of 18 centimetres for all genders, and weighs about 11 grams .
A typical Eurasian blue tit has an azure blue crown and dark blue line passing through the eye, and encircling the white cheeks to the chin, giving the bird a very distinctive appearance. The forehead and a bar on the wing are white. The nape, wings and tail are blue and the back is yellowish green. The underparts is mostly sulphur-yellow with a dark line down the abdomen - the yellowness is indicative of the number of yellowy-green caterpillars eaten, due to high levels of carotene pigments in the diet. The bill is black, the legs bluish grey, and the irides dark brown. The sexes are similar, but under ultraviolet light, males have a brighter blue crown. Young blue tits are noticeably more yellow.

Distribution

There are currently around 20–44 million pairs in Europe.

The Eurasian blue tit and the related hybrids are considered native species in areas of the European continent with a mainly temperate or Mediterranean climate, and in parts of the Middle East. These areas include the United Kingdom and most of the European Union and EFTA , plus: Albania, Algeria, Andorra, Armenia, Azerbaijan, Belarus, Bosnia and Herzegovina, Georgia, Iran, Iraq, Jordan, Kazakhstan, Lebanon, Libya, the Republic of Macedonia, Moldova, Montenegro, Morocco, Russia, San Marino, Serbia, Syria, Tunisia, Turkey, Vatican City and Ukraine.

Status

The Eurasian blue tit is classified as a Least Concern species on the IUCN Red List , and as a Green Status species, since 1996, by the Royal Society for the Protection of Birds in the United Kingdom.

Behavior

Eurasian blue and great tits form mixed winter flocks, and the former are perhaps the better gymnasts in the slender twigs. A Eurasian blue tit will often ascend a trunk in short jerky hops, imitating a treecreeper. As a rule the bird roosts in ivy or evergreens, but in harsh winters will nest wherever there is a suitable small hole, be it in a tree or nesting box. They are very agile and can hang from almost anywhere.

This is a common and popular European garden bird, due to its perky acrobatic performances when feeding on nuts or suet. It swings beneath the holder, calling "tee, tee, tee" or a scolding "churr".

Habitat

There are currently around 20–44 million pairs in Europe.

The Eurasian blue tit and the related hybrids are considered native species in areas of the European continent with a mainly temperate or Mediterranean climate, and in parts of the Middle East. These areas include the United Kingdom and most of the European Union and EFTA , plus: Albania, Algeria, Andorra, Armenia, Azerbaijan, Belarus, Bosnia and Herzegovina, Georgia, Iran, Iraq, Jordan, Kazakhstan, Lebanon, Libya, the Republic of Macedonia, Moldova, Montenegro, Morocco, Russia, San Marino, Serbia, Syria, Tunisia, Turkey, Vatican City and Ukraine.Eurasian blue and great tits form mixed winter flocks, and the former are perhaps the better gymnasts in the slender twigs. A Eurasian blue tit will often ascend a trunk in short jerky hops, imitating a treecreeper. As a rule the bird roosts in ivy or evergreens, but in harsh winters will nest wherever there is a suitable small hole, be it in a tree or nesting box. They are very agile and can hang from almost anywhere.

This is a common and popular European garden bird, due to its perky acrobatic performances when feeding on nuts or suet. It swings beneath the holder, calling "tee, tee, tee" or a scolding "churr".

Reproduction

The Eurasian blue tit will nest in any suitable hole in a tree, wall, or stump, or an artificial nest box, often competing with house sparrows or great tits for the site. Few birds more readily accept the shelter of a nesting box; the same hole is returned to year after year, and when one pair dies another takes possession. It is estimated by the RSPB that there are 3,535,000 breeding pairs in the UK.

The bird is a close sitter, hissing and biting at an intruding finger. In the South West of England such behaviour has earned the Eurasian blue tit the colloquial nickname "Little Billy Biter". When protecting its eggs it raises its crest, but this is a sign of excitement rather than anger, for it is also elevated during nuptial display. The nesting material is usually moss, wool, hair and feathers, and the eggs are laid in April or May. The number in the clutch is often very large, but seven or eight are normal, and bigger clutches are usually laid by two or even more hens. It is not unusual for a single bird to feed the chicks in the nest at a rate of one feed every ninety seconds during the height of the breeding season. In winter they form flocks with other tit species.

Food

The Eurasian blue tit is a valuable destroyer of pests, though it has not an entirely clean sheet as a beneficial species. It is fond of young buds of various trees, and may pull them to bits in the hope of finding insects. No species, however, destroys more coccids and aphids, the worst foes of many plants. It takes leaf miner grubs and green tortrix moths . Seeds are eaten, as with all this family.

Predators

The small size of the Eurasian blue tit makes it vulnerable to prey by larger birds such as jays who catch the vulnerable fledglings when leaving the nest. The most important predator is probably the sparrowhawk, closely followed by the domestic cat. Nests may be robbed by mammals such as weasels and red squirrels and grey squirrels in the UK.

The successful breeding of chicks is dependent on sufficient supply of green caterpillars as well as satisfactory weather. Breeding seasons may be affected badly if the weather is cold and wet between May and July, particularly if this coincides with the emergence of the caterpillars on which the nestlings are fed.